Also the studio was already known for quality and some of their own brands were already quite successful, making them more or less the top CRPG developer that also brought a lot of innovation to the genre. Although Baldurs Gate certainly is a brand that draws additional people. I could imagine that their other games will also get in the focus again when people are finished with the new title.
That said, all the games you mentioned were a success I believe. Maybe not that large, but I think they all were "surprisingly" successful compared to many AAA titles that wished they were.